Oxygen Atom Transfer and Intramolecular Nitrene Transfer in a Rhenium β-Diketiminate Complex.

We present two routes to the oxo rhenium complex OReCl2 (BDI) (1) (BDI = N,N'-bis(2,6-diisopropylphenyl)-β-diketiminate) and discuss the properties and reactivity of this material. Several adducts of 1 with DMAP (1-DMAP; DMAP = 4-dimethylaminopyridine), isonitriles (1-XylNC; XylNC = 2,6-dimethylphenyl isocyanide), and phosphines (1-PEt3 ; PEt3 = triethylphosphine) were isolated and characterized. Additionally, to probe the ancillary limitations of the BDI framework in high-valent rhenium complexes, oxygen atom transfer (OAT) reactivity with 1 was pursued. It was found that under thermolysis conditions OAT between 1 and PEt3 was observed by NMR spectroscopy, which indicated the formation of a new species, (ArN)ReCl2 (MAD)(PEt3 ) (2; Ar = 2,6-diisopropylphenyl, MAD = 4-((2,6-diisopropylphenyl)imino)pent-2-enide). A mechanism for the generation of 2 involving nitrene transfer to rhenium from the BDI ligand is proposed. X-ray crystal structures of complexes 1, 1-PEt3 , 1-DMAP, and 2 were determined and are discussed in detail.